The overall objective of this research is to study the structure, biogenesis and function of animal cell surfaces. This interest has been stimulated by recent observations relating cell surfaces with regulation of cellular growth. The specific purpose of this project is to understand the mechanism(s) of glycosylation (with particular emphasis on sialic acid) of glycolipids and glycoproteins. We will continue and extend to other sugar nucleotides our current studies on the subcellular site(s) of synthesis of CMP-sialic acid. Attempts will be made to determine how sugar nucleotides get from their intracellular site(s) of synthesis to the site(s) of sugar transfer. We will further pursue our recent observations on the uptake by cells of sialic acid and the subsequent incorporation of this sugar into glycoproteins and lipids. The intracellular site(s) where the covalent binding of sialic acid to glycoproteins and glycolipids occurs will be studied by pulse-chase kinetics with cells in tissue culture and mouse liver. Although initial experiments will monitor the glycosylation of a mixture of glycoprotens and lipids, future studies will concentrate on one particular glycoprotein. The subcellular movement of covalently bound label will be monitored by a combination of subcellular fraction and electron microscopy-autoradiography. These studies with normal cells will be extended to cells in tissue culture infected with a virus that is temperature sensitive for transformation since such a system should enable us to distinguish transformation related phenomena from ancillary ones.